Transact-SQL (T-SQL) functions are subprograms that encapsulate a sequence of T-SQL statements. T-SQL functions can return a single scalar value, a single row, or multiple rows.
There are two types
of T-SQL functions:
·
Scalar
functions: return a single scalar value, such as an integer, a string, or a
date/time value.
·
Table-valued
functions: return a table, allowing multiple rows to be returned and processed
like a physical table.
Some common T-SQL
functions include:
·
Aggregate
functions: COUNT, SUM, AVG, MIN, MAX, etc.
·
Date
and time functions: GETDATE, DATEADD, DATEDIFF, etc.
·
String
functions: LEN, SUBSTRING, CHARINDEX, etc.
·
Conversion
functions: CAST, CONVERT, etc.
System functions:
@@ROWCOUNT, @@IDENTITY, @@ERROR, etc.
Functions can be
used in T-SQL statements to manipulate data and simplify complex calculations.
